Structure of floor slab bridge

ABSTRACT

To properly construct a floor slab bridge by forming a main girder structure of the floor slab bridge in a bridge using commercially available columnar H-shaped steels and then applying concrete thereto. A construction of the floor slab bridge comprises a plurality of columnar H-shaped steels  1  each disposed between adjacent bridge legs  5, 5  and arranged in side-by-side relation with an end face  2   a  of a lower flange  2  abutted with a corresponding end face  2   a  of the adjacent columnar H-shaped steel  1 , a lower concrete layer  10  formed by placing concrete in space S defined between the upper and lower flanges  4  and  2  and between the adjacent web plates  3  through a concrete inlet port  8  formed between the adjacent upper flanges  2 , an upper concrete layer  11  formed by placing concrete  9  on the upper flange  4 , an iron reinforcement  12  is horizontally disposed on the upper flanges  4 , an iron reinforcement  13  being suspended in the space S from the horizontal iron reinforcement  12  through the concrete inlet port  8 , and the horizontal iron reinforcement  12  being embedded in the upper concrete layer  11  and the suspending iron reinforcement  13  being embedded in the lower concrete layer  10.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a structure of a floor slab bridge in abridge built up in river or on land, and more particularly to astructure of a floor slab bridge in which a columnar H-shaped steel isused as a main girder material.

[0003] 2. Related Art

[0004] A floor slab bridge is disclosed by Japanese Patent ApplicationLaid-Open Publication No. H09-221717 as typically illustrated in itsFIGS. 1 and 2, in which steel sheet piles 11 are used as a bottom plate,T-shaped steels or H-shaped steels (main girder member 13) are welded tothe steel sheet piles 11 such that the T-shaped steels or H-shapedsteels are spacedly arranged thereon, each and every adjacent steelsheet piles 11 are joined together by pawls 12 disposed at left andright side end faces of each steel sheet pile 11, concrete is placed inspace between an upper flange of each T-shaped steel or H-shaped steeland the steel sheet pile 11 through a concrete inlet port which isformed between the upper flanges of each T-shaped steel or H-shapedsteel so that a lower concrete layer is formed, and concrete is placedon the upper flange so that an upper concrete layer is formed, whichupper concrete layer is to be joined with the lower concrete layerthrough the concrete inlet port.

[0005] Similarly, FIG. 5 of the above publication shows a floor slabbridge in which a plurality of T-shaped steels or H-shaped steels arearranged in side-by-side relation on a bottom plate 3 composed of asingle steel plate and concrete is placed thereon.

[0006] In those floor slab bridges, a side plate 16 is applied to theouter side surface of the side concrete layer placed on the outer sidesurface of the leftmost or rightmost T-shaped steel or H-shaped steel,and in the floor slab bridge shown in FIGS. 1 and 2, a PC steel material18 is pierced through a web plate formed of T-shaped steel or H-shapedsteel, which are arranged in side-by-side relation, a lower concretelayer and a block which is called as a cross girder 19 from the outerside surface of the side plate 16, both ends of the PC steel material 18are fastened at the outer side surfaces of the side plates 16, and playat the joint part of the pawl 12 is set maximum, thereby applying apre-stress to the concrete layer. Necessarily, the PC steel material 18used as this pre-stress means is left in its exposed state at thefastening parts on its both ends at the outer side surfaces of the sideplates 16.

[0007] In the above-mentioned conventional structure(s), the bottomplate is formed by the steel sheet piles 11, and the T-shaped steels orH-shaped steels are spacedly arranged in side-by-side relation on thebottom plate as in the manner as mentioned above. Play at the joint partof the pawl 12 of the steel sheet pile 11 is set maximum. After theconcrete placed is cured, the PC steel material 18 is fastened at theouter side surfaces of the side plates 16, thereby applying a pre-stressto the concrete layer. The PC steel material 18 pierces through theblock, which is called as cross girder 19, with play, thus enabling torealize a fastening which can apply the pre-stress. Accordingly, the PCsteel material 18 is not joined with the concrete at all. This meansthat the PC steel material 18 does not function as a concretereinforcement.

[0008] Therefore, when a vertical load (live load) attributable topassage of vehicles, etc. should be applied to the floor slab bridge, ashearing force would act on the concrete layer which would induce crackof the concrete layer.

[0009] Moreover, since the PC steel material 18 is fastened at the outerside surfaces of the two side plates 16, the load is totally applied tothe fastening parts of the side plates 16, thus resulting in collapsingand/or twisting of the side plates 16.

[0010] In addition, since the fastening parts are exposed from the sideplates 16, i.e., from the concrete layer, the fastening parts are rottenby wind, rain or the like to degrade their original function and tospoil the outer appearance of the floor slab bridge.

[0011] Moreover, such a very troublesome work is required as to filletweld each and every T-shaped steel or H-shaped steel over its entirelength to the bottom plate 3 and the steel sheet piles 11 at constantintervals. Thus, the working term is increased and the cost isincreased, too.

[0012] The present invention has been accomplished in view of the aboveproblems.

SUMMARY OF THE INVENTION

[0013] It is, therefore, an object of the present invention to provide astructure of a floor slab bridge which can be properly formed by forminga main girder structure using commercially available columnar H-shapedsteels and applying concrete thereto.

[0014] In order to achieve the above object, from one aspect of thepresent invention, there is provided a structure of a floor slab bridgecomprising a plurality of columnar H-shaped steels each of whichincludes a web plate having at an upper end thereof an upper flange andat a lower end thereof a lower flange, the columnar H-shaped steelsbeing arranged in side-by-side relation with an end face thereof abuttedwith a corresponding end face of the adjacent columnar H-shaped steel,the upper flanges being smaller in width than the lower flanges so thata concrete inlet port is formed between adjacent upper flanges; a lowerconcrete layer formed by placing concrete in space defined between theupper and lower flanges and between the adjacent web plates through theconcrete inlet port; an upper concrete layer formed by placing concreteon the upper flange and connected to the lower concrete layer throughthe concrete inlet port; a horizontal iron reinforcement horizontallylaid on each of the upper flanges; a suspending iron reinforcementsuspending in the space through the concrete inlet port; and thehorizontal iron reinforcement being embedded in the upper concrete layerand the suspending iron reinforcement being embedded in the lowerconcrete layer.

[0015] By the horizontal iron reinforcement and the suspending ironreinforcement suspended therefrom, the joining strength between theupper concrete layer and the lower concrete layer, particularly thelower concrete layer demarcated by the web plate is properly reinforced,thereby enabling to provide a sufficient strength to the entire floorslab bridge.

[0016] Thus, the shearing resisting force of the concrete against thelive load is increased to effectively prevent crack.

[0017] The columnar H-shaped steels generally of JIS specifications eachhaving an upper flange which is cut in such a manner as to have apredetermined width are arranged in side-by-side relation betweenadjacent bridge legs with the adjacent lower flanges abutted with eachother and concrete is placed thereon. Merely by doing so, a floor slabbridge can be constructed at a low cost and in a short working term.

[0018] From another aspect of the present invention, there is provided astructure of a floor slab bridge comprising a plurality of columnarH-shaped steels each of which includes a web plate having at an upperend thereof an upper flange and at a lower end thereof a lower flange, ajoining plate made of a steel material being interposed between everyadjacent lower flanges, left and right end faces of each of the joiningplates being in abutment relation with corresponding end faces of lowerflanges of the adjacent left and right columnar H-shaped steels, aconcrete inlet port being formed between every adjacent upper flangeswith the help of the joining plate; a lower concrete layer formed byplacing concrete in space formed between the upper and lower flanges andbetween the adjacent web plates through the concrete inlet port; and anupper concrete layer formed by placing concrete on the upper flange andconnected to the lower concrete layer through the concrete inlet port.

[0019] By employment of the joining plate, the time and labor fordimensioning the upper flange smaller in width than the lower flange canbe eliminated. The columnar H-shaped steels of JIS specifications can beused as they are. Accordingly, a floor slab bridge can be constructed ata low cost and in a short working term. Moreover, by properly selectingthe width of the joining plate, the width dimension of the bridge can beset easily.

[0020] From a further aspect of the present invention, there is provideda structure of a floor slab bridge comprising a plurality of columnarH-shaped steels each of which includes a web plate having at an upperend thereof an upper flange and at a lower end thereof a lower flange,the columnar H-shaped steels being arranged in side-by-side relationwith an end face thereof abutted with a corresponding end face of theadjacent columnar H-shaped steel, the web plate being piercedtherethrough by a web through-bar, a plurality of the web through-barsbeing arranged in the longitudinal direction of the bridge at smallintervals, a stopper such as a nut, which is to be abutted with an outerside surface of each of the leftmost and rightmost columnar H-shapedsteels, the upper flanges being smaller in width than the lower flangesso that a concrete inlet port is formed between adjacent upper flanges;a lower concrete layer formed by placing concrete in space definedbetween the upper and lower flanges and between the adjacent web platesthrough the concrete inlet port; an upper concrete layer formed byplacing concrete on the upper flange and connected to the lower concretelayer through the concrete inlet port; and the web through-bar beingembedded in the lower concrete layer so as to serve as a concretereinforcement, opposite ends of the web through-bar and the stopperbeing embedded in side concrete layers which are placed on outer sidesurfaces of the leftmost and rightmost columnar H-shaped steels.

[0021] The web through-bar is preferably of the type having a head(stopper) at one end thereof. A nut (stopper) is threadingly engagedwith the other end of the web through-bar so as to fasten to the outerside surfaces of the web plate of the leftmost and rightmost columnarH-shaped steels. It is also accepted that a nut is threadingly engagedwith each end of the web through-bar to fasten to the outer sidesurfaces of the leftmost and rightmost columnar H-shaped steels.

[0022] This fastening force is preferably not so large as to give anabutting force to the abutting parts of the adjacent lower flanges ofthe columnar H-shaped steels. That is, it is preferred that the adjacentlower flanges of the columnar H-shaped steels are merely looselycontacted (a small space may be formed between the adjacent lowerflanges) with each other.

[0023] The web through-bar is embedded in the lower concrete layer so asto serve as a concrete reinforcement. Moreover, the shearing resistingforce against the live load to be imposed on the concrete layer isincreased. This prevents concrete crack effectively. In addition, byembedding the stoppers and opposite end parts of the web through-bar inthe side concrete layers, they can be prevented from being rotten bywind, rain or the like and the outer appearance is not spoiled.

[0024] Preferably, the joining plate is provided with a reinforcementplate which is erected from an upper surface of the joining plate andembedded in the lower concrete layer. Owing to this arrangement, themain girder component members of a bridge can be more increased instrength, and the joining plate and the lower concrete layer can befirmly joined together.

[0025] The horizontal iron reinforcement and the suspending ironreinforcement may be used in combination with the joining plate and theweb through-bar, where appropriate. By doing so, those elements can besynergically functioned.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a lateral sectional view showing a structure of a floorslab bridge formed of a columnar H-shaped steel and by concreteplacement.

[0027]FIG. 2 is a plan view showing a state of columnar H-shaped steelsset up in side-by-side relation for construction of a bridge before aconcrete placement is made.

[0028]FIG. 3 is a side view thereof.

[0029]FIG. 4 is a lateral sectional view showing an example in which aconcrete inlet port is formed in the columnar H-shaped steel.

[0030]FIG. 5 is a lateral sectional view showing another example inwhich a concrete inlet port is formed in the columnar H-shaped steel.

[0031]FIG. 6 is a lateral sectional view showing an example of the floorslab bridge in which joining plates are used.

[0032]FIG. 7 is a cross sectional view exemplifying a relation among thejoining plate, the columnar H-shaped steels and web through-bars.

[0033]FIG. 8 is a cross sectional view of a floor slab bridge showing anexample in which a light-weight material is applied to the bridge.

[0034]FIG. 9 is a side view thereof.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] Embodiments of the present invention will now be describedhereinafter with reference to FIGS. 1 through 9.

[0036] As shown in FIGS. 1, 2, 6 and 8, a plurality of columnar H-shapedsteels 1 each having an lower flange 2 and an upper flange 4 joinedtogether through a web plate 3, that is, a plurality of commerciallyavailable H-shaped steels of JIS specifications, are used. As shown inFIGS. 2, 3 and 9, those columnar H-shaped steels 1 are arranged inside-by-side relation between adjacent bridge legs 5 such that end faces2 a of the adjacent lower flanges 2 are abutted with each other.

[0037] As shown in FIGS. 3 and 9, the opposite ends of the columnarH-shaped steel 1 are supported on seat surfaces of the adjacent bridgelegs 5, 5 through rubber bearings 6 or the like, and the opposite endsof the lower flange 2 are attached to the bridge legs 5 through anchorbolts 7.

[0038] As shown in FIG. 4, each upper flange 4 is dimensioned smaller inwidth than each lower flange 2, so that a concrete inlet port 8 of FIG.1 is formed between the adjacent upper flanges 4.

[0039] As the columnar H-shaped steel 1, a steel column of JISspecifications (JISG3101 steel material, JISG3106 steel material,JISG3114 steel material) which is composed of a lower flange 2, an upperflange 4 and a web plate 3 is used. As shown in FIG. 4, opposite endparts of the upper flanges 4 of the respective columnar H-shaped steels1 are cut off by same width portions so that the upper flanges 4 aresmaller in width than the lower flanges 2. Those columnar H-shapedsteels 1 having such dimensioned upper and lower flames 4, 2 areprepared beforehand and carried in site.

[0040] As shown in FIG. 5, one half part of the upper flange 4 of eachcolumnar H-shaped steel 1 is cut off at the joining part with respect tothe web plate 3. A plurality of columnar H-shaped steels 1 each havingsuch an upper flange 4 are arranged in side-by-side relation with theadjacent lower flanges 2 abutted with each other to thereby form theconcrete inlet port 8.

[0041] As shown in FIG. 1, concrete 9 is placed in space S which isdefined between each upper and lower flanges 4, 2 and between theadjacent web plates 3 through the concrete inlet port 8 so that a lowerconcrete layer 10 is formed.

[0042] Moreover, the concrete 9 is placed on each upper flange 4 to forman upper concrete layer 11 which is connected to the corresponding lowerconcrete layer 10 through the concrete inlet port 8.

[0043] Plating such as zinc plating, or coating is applied to the outersurface of the columnar H-shaped steel 1.

[0044]FIG. 6 shows another example. As shown in FIG. 6, a plurality ofcolumnar H-shaped steels of JIS specifications are supported betweenadjacent bridge legs 5 without applying width cutting treatment to theupper flanges 4. Lower flanges 2 with a steel-made joining plate 15interposed between every adjacent lower flanges 2 are supposed betweenthe adjacent bridge legs 5. One end face 15 a of each joining plate 15is arranged in abutment relation with a corresponding end face 2 a ofthe adjacent lower flange 2 and the other end face 15 a of each joiningplate 15 is arranged in abutment relation with the other end face 2 a ofthe adjacent lower flange 2. A concrete inlet port 8 is formed betweenevery adjacent upper flanges 4 with the help of the joining plate 15. Asshown in FIGS. 6 and 8, concrete is placed in space S′ formed betweenthe upper flange 4 and the lower flange 2 and between the adjacent webplates 3 through the concrete inlet port 8 to thereby form a lowerconcrete layer 10.

[0045] Then, concrete is placed on each upper flange 4 to form an upperconcrete layer 11 which is connected to the lower concrete layer 10through the concrete inlet port 8.

[0046] In the example of FIG. 1, the columnar H-shaped steels 1 of JISspecifications each having an upper flange 4 which is cut in such amanner as to have a predetermined width are arranged in side-by-siderelation between the adjacent bridge legs 5 and concrete is placedthereon. Merely by doing so, a floor slab bridge can be constructed at alow cost and in a short working term.

[0047] In the example of FIGS. 6 and 8, a plurality of columnar H-shapedsteels 1 of JIS specifications are supported between adjacent bridgelegs 5 without applying width cutting treatment to the upper flanges 4,and concrete 9 is placed thereon. Merely by doing so, a floor slabbridge can be constructed at a low cost and in a short working term.

[0048] As shown in FIGS. 1, 6 and 8, a form side plate 14 is assembledto the outer side of each of the leftmost and rightmost columnarH-shaped steels 1′ (each columnar H-shaped steel located at the leftextreme end or at the right extreme end in the width direction of thebridge), and concrete is placed on the outer side part of the columnarH-shaped steel 1′ to thereby form a side concrete layer 10′.

[0049] In other words, concrete 9 is placed in space S″ which is definedby the lower flange 2, the web plate 3, the upper flange 4 and the formside plate 14 of the columnar H-shaped steel 1′ to thereby form a sideconcrete layer 10′.

[0050] The form side plates 14 are removed after the concrete 9 iscured. In actual practice, the lower concrete layer 10, the upperconcrete layer 11 and the side concrete layers 10′ are not formed byplacing the concrete 9 separately. Instead, by continuously placing theconcrete 9, the side concrete layers 10″ are integrally formed (orplaced) on the opposite ends of the upper concrete layer 11. A parapet21 is integrally erected on the upper end of each concrete layer 10′.

[0051] Each joining plate 15 has a generally same thickness as the lowerflange 2. The joining plates 15 and the columnar H-shaped steels 1 arealternately arranged between the bridge legs 5.

[0052] The joining plate 15 makes it possible to form the concrete inletport 8 in case the commercially available columnar H-shaped steel 1 isused in which steel 1, the upper flange 4 is not partly cut off. Thewidth dimension is established by properly selecting the width of htjoining plate 15.

[0053] As shown in FIGS. 6, 7 and 8, each joining plate 15 is providedwith a reinforcement plate 18 which is erected from the center of theupper surface thereof and embedded in the lower concrete layer 10. Thejoining plate 15 in combination with the reinforcement plat 18 exhibit aT-shaped configuration. Therefore, either by applying the commerciallyavailable T-shaped steel, or a T-shaped steel is formed by partlycutting off the upper flange of the commercially available columnarH-shaped steel, and the joining plate 15 and the reinforcement plate 18are formed.

[0054] As shown in FIG. 7, the reinforcement plate 18 is provided at anupper end thereof with a flange 19 which is integral with the joiningplate 15 and the reinforcement plat 18 and in parallel with the joiningplate 15. That is, a steel material, which includes the joining plate15, the reinforcement plate 18 and the flange 19, is in the form of thecolumnar H-shaped steel. The commercially available columnar H-shapedsteel 1 of JIS specifications thereto, the joining plate 15 is formed bythe lower flange of the commercially available columnar H-shaped steel1, and the joining plate 18 and the upper flange 19 are embedded in thelower concrete layer 10.

[0055] In the same manner as described above, plating such as zincplating, or coating is applied to the outer surface of the columnarH-shaped steel 1. Similarly, plating such as zinc plating, or coating isapplied to the outer surface of the columnar T-shaped or H-shaped steelwhich constitutes the joining plate 15 and the reinforcement plate 18.

[0056] By the reinforcement plate 18 and upper flange 19, the maingirder component member of a bridge is further increased in strength andthe joining plate 15 and the lower concrete layer 10 are firmlyconnected together. Of course, the columnar H-shaped steel composing thejoining plate 15 is smaller enough than the columnar H-shaped steelwhich composes the main girder.

[0057] Moreover, an iron reinforcement is horizontally laid on the upperflange 4, and the suspending iron reinforcement 13 is assembled with thehorizontal iron reinforcement 12. The suspending iron reinforcement 13is suspended in the space S, S′ through the concrete inlet port 8. Thehorizontal iron reinforcement 12 is embedded in the upper concrete layer11, and the suspending iron reinforcement 13 is embedded in the lowerconcrete layer 10. By doing so, a floor slab bridge can be constructed.

[0058] In the same manner as mentioned above, the suspending ironreinforcements 13 are suspended in the left and right outer space S″ ofthe leftmost and rightmost columnar H-shaped steels 1′, and thesuspended iron reinforcements 13 are embedded in the side concretelayers 10′.

[0059] Each suspending iron reinforcement 13 is, as shown in FIG. 1,formed in a U-shaped configuration in the width direction of the bridge,and, as shown in FIG. 6, formed in a U-shaped configuration in thelongitudinal direction of the bridge. The opposite upper ends of eachsuspending iron reinforcement 13 are assembled with the horizontal ironreinforcement 12 in a suspending manner.

[0060] The horizontal iron reinforcement 12 is supported on the uppersurface of the upper flange 4 so as to bear the horizontal ironreinforcement 12 and suspending iron bar 13. Of course, a plurality ofsuch plural iron reinforcements 12, 13 are arranged at small intervalsin the longitudinal direction of the H-shaped steel 1.

[0061] Moreover, vertical iron reinforcements 12′ extending in thelongitudinal direction of the bridge are assembled with the horizontaliron reinforcements 12 and the suspending iron reinforcements 13 so asto form a basket shape as a whole. Those vertical iron reinforcements12′ are also supported on the horizontal iron reinforcements 12 whichare horizontally supported on the upper flanges 4.

[0062] By the horizontal iron reinforcements 12 and the suspending ironreinforcements 13 suspended therefrom, the joining strength between theupper concrete layer 11 and the lower concrete layer 12, particularlythe lower concrete layer 10 demarcated by the web plate 3 is properlyreinforced, thereby enabling to provide a sufficient strength to theentire floor slab bridge.

[0063] Thus, the shearing resisting force of the concrete 9 against thelive load is increased to effectively prevent crack of the upper andlower concrete layers 11, 10.

[0064] As another example, as shown in FIGS. 1, 5 and 8, a through hole3 a is formed in each web plate 3 of the columnar H-shaped steel 1 inwhich the adjacent lower flanges 2 are directly or indirectly abuttedwith each other. A web through-bar 16 is allowed to pierce through thisthrough hole 3 a. As shown in FIGS. 3 and 9, a plurality of such webthrough-bars 16 are arranged at small intervals in the longitudinaldirection of the bridge. Each web through-bar 16 is provided at bothends thereof with stoppers 17 such as nuts which are to be abutted withthe outer side surfaces of the web plates 3 of the leftmost andrightmost columnar H-shaped steels 1′.

[0065] As shown in FIG. 3, a plurality of such web through-bars 16 arearranged in a single row at small intervals in the longitudinaldirection of the bridge. Alternatively, as shown in FIG. 9, the webthrough-bars 16 are arranged in upper and lower rows.

[0066] Each web through-bar 16 is embedded in the lower concrete layer10 which is formed by placing the concrete through the concrete inletport 8, so as to serve as a concrete reinforcement.

[0067] The both ends of each web through-bar 16 and each stopper 17 areembedded in the side concrete layers 10′ which a formed by placing theconcrete on the outer side surfaces of the leftmost and rightmostcolumnar H-shaped steels 1′.

[0068] The web through-bar 16 is preferably of the type having a head(stopper 17) at one end thereof. A nut (stopper 17) is threadinglyengaged with the other end of the web through-bar 16 so as to fasten tothe outer side surfaces of the web plate 3 of the leftmost and rightmostcolumnar H-shaped steels 1′. It is also accepted that a nut isthreadingly engaged with each end of the web through-bar 16 so as tofasten to the outer side surfaces of the leftmost and rightmost columnarH-shaped steels 1′.

[0069] This fastening force is preferably not so large as to give anabutting force to the abutting parts of the adjacent lower flanges 2 ofthe columnar H-shaped steels. That is, it is preferred that the adjacentlower flanges of the columnar H-shaped steels 1 are merely looselycontacted (a small space may be formed between the adjacent lowerflanges) with each other.

[0070] The web through-bar 16 is embedded in the lower concrete layer 10so as to serve as a concrete reinforcement. That is, as shown in FIG. 1,when a vertical load A attributable to passage of vehicles, etc. shouldbe applied to the floor slab bridge, shearing force B would act on thejoining part between the columnar H-shaped steel 1 (or joining plate 15)which is under the load and its adjacent columnar H-shaped steel 1 (orjoining plate 15) and the concrete layers 10, 11 corresponding to thejoining part. However, the web through-bar 16 effectively prevents theinduction of crack (shearing) occurrable to the concrete layers 10, 11caused by the vertical load A.

[0071] Similarly, the horizontal iron reinforcement 12 and thesuspending iron reinforcement 13 in combination with the concrete 9(concrete layers 10, 11) increase the shearing preventive effect. Theiron reinforcements 12, 13 may be used in combination with the webthrough-bar 16. By embedding the stoppers and the opposite ends of theweb through-bars in the side concrete layers, they can be prevented frombeing rotten by wind and rain and the outer appearance is not spoiled.Moreover, the web through bars 16 can be kept wholesome so that they canfully exhibit their function in spite of passage of time.

[0072] As shown in FIGS. 6, 7 and 8, in case a reinforcement plate 18 iserected from each joining plate 15, a through hole 18 a may be formed ineach reinforcement plate 18 so that the web through-bar 16 can piercethrough the through hole 18 a in the manner as mentioned above.

[0073] As still another example, as shown in FIGS. 8 and 9, alight-weight material 20 such as foamed resin or foamed concrete isdisposed in each space S′ which is defined among each upper flange 4,each web plate 3, each lower flange 2 and each joining plate 15, or inthe example of FIG. 1, in each space S which is defined among each upperflange 4, each web plate 3 and each lower flange 2, and embedded in thelower concrete layer 10.

[0074] The light-weight material 20 is preferably in the form of arectangular block. This light-weight material 20 is interposed betweenadjacent web plates 3 and intimately contacted therewith. Thelight-weight material 20 is placed and supported on the upper flange 19or reinforcement plate 18 of the columnar H-shaped steel.

[0075] A plurality of such light-weight materials 20 are, as shown inFIG. 9, arranged in the longitudinal direction of the bridge so as notto interfere with the web through-bars 16. By doing so, while increasingthe thickness of the lower concrete layer 10, i.e., by using a largesized columnar H-shaped steel 1 having a large height, the overallweight can be reduced (reduction of dead load) in spite of the increasedthickness of the entire floor plate which is required for filling thelight-weight material 20 therein.

[0076] The light-weight material 20 is embedded in the central part ofthe lower concrete layer 10, while the web through-bars 16 are insertedin the lower concrete layer part on the upper flange 4 side and in thelower concrete layer part on the lower flange 2 side which aredemarcated by the light-weight material 20.

[0077] The web through-bar 16, which is inserted into the lower concretelayer part on the lower flange 2 side, is inserted in the reinforcementplate 16 and embedded in the concrete 9. As shown in FIG. 6, even incase the light-weight material 20 is not filled, the web through-bar 16may be inserted in the reinforcement plate 18.

[0078] The suspending iron reinforcement 13 and the web through-bar 16are provided in the upper space of the light-weight material 20 and theconcrete 9 is placed thereon, and then embedded in the lower concretelayer part on the upper flange 4 side.

[0079] A plurality of iron reinforcements 13′ each formed in the shapeof a ring are arranged in the widthwise direction and in thelongitudinal direction of the bridge within the space in a lower part ofthe light-weight material 20, and the vertical iron reinforcements 12′are assembled with the ring-shaped iron reinforcements 13′ so as to forma basket shape, and embedded in the concrete layer filled in the lowerspace, i.e., in the lower concrete layer part on the lower flange 2side.

[0080] The horizontal iron reinforcements 12 and the suspending ironreinforcements 13 may be used in combination with the joining plates 15and the web through-bars 16, where appropriate. By doing so, thoseelements can be synergically functioned.

What is claimed is:
 1. A structure of a floor slab bridge comprising: aplurality of columnar H-shaped steels each of which includes a web platehaving at an upper end thereof an upper flange and at a lower endthereof a lower flange, said columnar H-shaped steels being arranged inside-by-side relation with an end face thereof abutted with acorresponding end face of the adjacent columnar H-shaped steel, saidupper flanges being smaller in width than said lower flanges so that aconcrete inlet port is formed between adjacent upper flanges; a lowerconcrete layer formed by placing concrete in space defined between saidupper and lower flanges and between the adjacent web plates through saidconcrete inlet port; an upper concrete layer formed by placing concreteon said upper flange and connected to said lower concrete layer throughsaid concrete inlet port; a horizontal iron reinforcement horizontallylaid on each of said upper flanges; a suspending iron reinforcementsuspending in said space through said concrete inlet port; and saidhorizontal iron reinforcement being embedded in said upper concretelayer and said suspending iron reinforcement being embedded in saidlower concrete layer.
 2. A structure of a floor slab bridge comprising:a plurality of columnar H-shaped steels each of which includes a webplate having at an upper end thereof an upper flange and at a lower endthereof a lower flange, a joining plate made of a steel material beinginterposed between every adjacent lower flanges, left and right endfaces of each of said joining plates being in abutment relation withcorresponding end faces of lower flanges of the adjacent left and rightcolumnar H-shaped steels, a concrete inlet port being formed betweenevery adjacent upper flanges with the help of said joining plate; alower concrete layer formed by placing concrete in space formed betweenthe upper and lower flanges and between the adjacent web plates throughsaid concrete inlet port; and an upper concrete layer formed by placingconcrete on said upper flange and connected to said lower concrete layerthrough said concrete inlet port.
 3. A structure of a floor slab bridgeaccording to claim 2, wherein said joining plate is provided with areinforcement plate a part of which is erected from an upper surface ofsaid joining plate and the rest of which is embedded in said lowerconcrete layer.
 4. A structure of a floor slab bridge comprising: aplurality of columnar H-shaped steels each of which includes a web platehaving at an upper end thereof an upper flange and at a lower endthereof a lower flange, said columnar H-shaped steels being arranged inside-by-side relation with an end face thereof abutted with acorresponding end face of the adjacent columnar H-shaped steel, said webplate being pierced therethrough by a web through-bar, a plurality ofsaid web through-bars being arranged in the longitudinal direction ofsaid bridge at small intervals, a stopper such as a nut, which is to beabutted with an outer side surface of each of the leftmost and rightmostcolumnar H-shaped steels, said upper flanges being smaller in width thansaid lower flanges so that a concrete inlet port is formed betweenadjacent upper flanges; a lower concrete layer formed by placingconcrete in space defined between the upper and lower flanges andbetween the adjacent web plates through said concrete inlet port; anupper concrete layer formed by placing concrete on said upper flange andconnected to said lower concrete layer through said concrete inlet port;and said web through-bar being embedded in said lower concrete layer soas to serve as a concrete reinforcement, opposite ends of said webthrough-bar and said stopper being embedded in side concrete layerswhich are placed on outer side surfaces of the leftmost and rightmostcolumnar H-shaped steels.